fatty acids

Organic acids consisting of long, straight hydrocarbon
chains which terminate in a carboxyl group
(-COOH) and have an even number of carbon
atoms. Many fatty acids occur in living things as components of lipids,
including triglycerides. Some fatty
acids can be synthesized by the body; others, the essential fatty
acids, must be obtained from the diet.

Natural fatty acids commonly have a chain of 4 to 28 carbons (usually unbranched
and even-numbered), which may be saturated or unsaturated. The most important
of saturated fatty acids are butyric (C4), lauric (C12), palmitic (C16),
and stearic (C18). The most common unsaturated acids are oleic, linoleic,
and linolenic (all C18).